1. Field
Embodiments relate to a calibration apparatus and method of three-dimensional (3D) position and direction estimation system, and more particularly, to an apparatus and method for calibrating a signal attenuation characteristic in a 3D position/direction estimation apparatus and method based on intensity information.
2. Description of the Related Art
Technology for estimating a three-dimensional (3D) position and a direction of a moving object or target may be used to sense a motion of an object, a human body, an animal, and the like within a 3D space using expensive and large motion capturing equipment in the field of graphics/animation industries and the like.
Consumer electronics (CE) motion sensing technology associated with game industry is gaining attention and thus, many 3D position and direction estimation methods using inexpensive and small motion capturing devices have been developed.
For example, a method of estimating a 3D position in a space may generally include a method of using a camera, a method of using an infrared ray, and a method of using an inertia sensor.
In the case of using a camera, it is possible to convert a position of a marker/light source focused within a camera image to a spatial 3D position using a plurality of two-dimensional (2D) cameras. However, accuracy depends on a camera resolution, a marker size, and the like. Thus, it is difficult to perform highly accurate sensing.
In the case of using an ultrasonic wave, when time of flight (TOF) of an ultrasonic wave from a transmitter to a receiver is measured using an aspect that an ultrasonic wave moves at the velocity of sound, for example, about 340 m/s in the air, a distance may be calculated. When information about at least three same view distances is obtained, the 3D position may be calculated. In the case of using an ultrasonic wave, it is possible to perform highly precise sensing with inexpensive equipment compared to expensive equipment such as a camera. However, due to interference between sound waves, signals may not be simultaneously transmitted. Considering an ultrasonic signal attenuation time, for example, about 100 m/sec for 3 m, it may be difficult to estimate a position of a moving object in real time.
In the case of using an inertia sensor, it is possible to estimate a 3D position by integrating acceleration, motion and gravitation acceleration that are obtained using a gyro sensor, and a motion acceleration component that is calculated using angular velocity. However, errors may be accumulated over time. That is, the above method may perform a position estimation only within a short time interval and thus, may not be suitable for the position estimation within a long time interval.
To solve the above problems, a method of estimating a 3D position and a direction using a signal attenuation characteristic of infrared ray is proposed. However, even in the case of using the signal attenuation characteristic, the signal attenuation characteristic may be differently sensed based on a characteristic of a receiver to receive a signal. Thus, the accuracy may be decreased.